British Style 50W Guitar Tube Amp Kit


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SKU: 0755818
Weight: 26.5 lb
Sale Unit: Piece

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Amp Kit Difficulty Level


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Please read our article 'Mojotone Amp Kit Building Primer' along with our amp kit disclaimer located in the Specs tab before buying this kit.

Ever heard of a guitarist named Randy Rhoads? Or how about the Young brothers from a little band called AC/DC?  They are just some of the artists that come to mind who used the late 70's JMP 2204.

In the mid-seventies, rock artists wanted a bit more gain and a lot more power from their stage amplifiers.  In response, Jim Marshall and crew developed the master volume function, added it to their plexi platform, and released the new circuit as the JMP 2203 and 2204 models.  With this new feature, the artist could crank the amplitude of the preamp output as they would with earlier, non-master models, to get an exciting distorted breakup of the signal. Then, they could adjust the overall output level to the speakers using the master volume control so that it sat nicely in the mix with the rest of the band.  From there, we experienced a total overhaul of the rock and roll sound.  Bands got heavier, and the solo leads soared higher than ever.  

We are happy to add the 50 Watt version (2204) to our British series kit lineup.  We had the opportunity to study an example from 1979 to create the near-replica chassis and head shell.  For transformers and choke, we offer the same tried and true units from our British 50W 800 kit.  The big difference between our kit and the original is the use of an old-school turret board instead of the printed circuit board that Marshall had employed.  We think this will offer more fun and future serviceability to the build.

As with all of our amplifier kits, we supply you with the best electronic components available.  You will see Mojo Dijon polypropylene capacitors, Mojotone high-voltage can style filtering capacitors, carbon film resistors, Belton brand tube sockets, Alpha potentiometers, 20 gauge topcoat PVC wire, and more.

As a bonus, we supply everything needed to build either the 1976-1978 2204 which is more of a hybrid between the earlier plexi and later JCM800 circuits, or the 1978-1980 2204 which features a bit more gain akin to the JCM 800 era.  Which one you build is up to you and your tastes.

  • Class Type: AB All Tube Amplifier
  • Output: ~50 Watts
  • Circuit: 1976-1980 2204
  • Bias Type: Fixed Bias
  • Build Time: ~8 hours
  • Preamp Tubes: ECC83/12AX7 (3)
  • Output Tube(s): EL34 (2)
  • Rectifier Tube: None - Solid-state Rectified
  • Transformers: Power - Plexi / 800 50W (7020850), Output - Plexi / 800 50W (7021850), Choke - Plexi / 800 Choke (7022800)
  • Hardware: Mojotone British 50W Small Parts Kit, British 50W Chassis, Front & Rear Faceplates

Disclaimer: Some of the parts contained in this kit are subject to availability.

Mojotone reserves the right to change or substitute any and all of the parts contained in this amplifier kit without advertisement or notification to the buyer. Part substitutions made by Mojotone are guaranteed not to affect the integrity or operation of your amplifier kit. Time estimates listed are from start to finish. If you are new to tube amplifiers, additional time may need to be factored.


When purchasing a kit from Mojotone, you will receive the following documentation.

1. Schematic

2. Wiring Diagram / Layout

Our beginner level kits such as the tweed champ and tweed deluxe include a manual. If you purchase a kit from Mojotone and do not receive these documents, you can obtain copies by emailing or calling 800-927-6656. The Mojotone staff is available Monday through Friday from 8:30 a.m. to 5:00 p.m. EST unless otherwise closed.


Mojotone kits include the best quality parts that are available at the time of purchase. If a substitution is required, our team will use parts that are of equal quality to ensure the integrity of the kit build remains the same.


Building a fully functional amplifier kit is not an easy task. Before building a kit, one should have the ability to properly solder as well as read and understand a schematic and wiring diagram. While we do our very best to ensure all documentation is current, the included documentation is meant to serve as an overall guide to building the amplifier. Simply following the schematic and wiring diagram does not guarantee you will have a fully functional amplifier. In fact, post build troubleshooting is a common issue across all builds.


Our staff is available to assist with basic troubleshooting needs. There are plenty of online videos available that are helpful with most post build issues. Technical staff is available via email by sending a message to You may also call our sales team to discuss build problems, dial 800-927-6656 and press 1 for sales.


Building a tube amplifier takes time, dedication, resources and most importantly... Skills! The experience of building an amp can come with some frustration, the reward of completing the build is definitely well worth your time. Please review the wiring diagram, schematic and manual (if applicable) prior to making your purchase. Mojotone will not accept any returns on amplifier kits and/or parts that have been assembled, soldered or modified.

This amp kit also comes with the following documents. Please feel free to view and/or download them:

British 50W 1976 2204 Schematic

British 50W 1976 2204 Wiring Diagram

British 50W 1978 2204 Schematic

British 50W 1978 2204 Wiring Diagram



Product Demo

Ratings & Reviews

8 reviews

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3/22/2024 5:07 pm

Crunch Time is here

by Big Swifty -

All the other reviews are spot on with this high quality kit! I built the 1978 version and it absolutely rocks at ANY volume level. The amp was biased cool and the clean tones are amazing. It’s pumped into a (2) 12 cabinet loaded with 50 watt Weber Silver Bells. Big low end thump, and crystal clear highs, and it’s a crunch monster cranked. The sound I’ve always dreamed from my Les Paul. Kudos Mojotone!

1/19/2024 7:19 am

JMP Heaven

by Jesse -

I normally don’t write reviews, but I had to on this amp kit. Every single part is high quality, the wiring diagram and schematic are easy to follow, just double and triple check all your work. This was my first amp build, and I’m beyond pleased with how it turned out. If you have any hesitation, I wouldn’t. Just order this kit, you won’t regret it!!!